Schools in disadvantaged areas are making the most progress at GCSE level, schools minister Jim Knight said yesterday.

The results in 134 out of 149 local authorities rose this year, but Mr Knight said those with "challenging circumstances" were advancing the most.

However, political opponents were quick to seize on the fact that fewer than half of teenagers scored at least five C grades in subjects including maths and English.

Among those areas which showed the most improvement were Halton, on Merseyside, where the number of pupils getting five A* to C GCSEs rose 8.5 percentage points, and Salford, which recorded an increase of 7.7 percentage points.

In Hackney and Southend, the percentage of pupils getting five good GCSEs including maths and English has risen by 4.7 points since 2006, according to the figures published by the Department for Children, Schools and Families (DCSF).

Over the last 10 years, pupils getting five A* to C-grade GCSEs in Tower Hamlets improved the most - by 30.1 percentage points - while in Hackney it rose by 24 points. "Local authorities have a responsibility to help drive up standards by intervening early to address slow or poor performance," said Mr Knight. "I am challenging all LAs to do what the best are doing." But he conceded that individual pupils still needed attention, even if schools were improving.

"The trend is clear, and we are being successful and narrowing the gap in attainment between advantaged and disadvantaged schools. But when you look at it on a per-pupil basis, the gap isn't widening, but it's not narrowing either," he said. "That's not good enough for us, and we want to do better."

Mr Knight vowed to increase the pace of improvement, narrowing the gap between the highest and lowest attainers. He said one failing school would be closed and eight turned into academies.

The 20 academies that have been open long enough to have results in 2006 and 2007 saw a 6.1 percentage point improvement in the proportion of pupils getting five or more A* to C grades at GCSE, or 3.6 percentage points including maths and English - above the 1 percentage point improvement nationally. "Academies are outperforming their predecessor schools and show significant rates of improvement," Mr Knight said.

He added that the government had passed its target of 60% of pupils achieving five A* to C grades in their GCSEs by 2008. According to the department's figures, 61.5% of key stage 4 (year 11, age 16) pupils in England scored five A* to C grades this summer, up 2.3 percentage points. And 46.5% of pupils achieved at least five A* to C grades, including maths and English, up 0.7 percentage points on last year.

Mr Knight said the government would not be complacent. To reach the target of at least 53% of young people getting five good GCSEs including English and maths by 2011 would require "a doubling of the current rate of improvement".

"Whatever the carping from the usual doom-mongers, 470,000 more young people since 1997 have got a better start in life," he said.

"There's been significant progress after inheriting a dire legacy - over half of schools had less than three in 10 pupils getting five GCSEs, including English and maths, 10 years ago. We've slashed that shocking figure to under a quarter."

Girls continued to outperform boys at GCSE, particularly in the higher grades. Two-thirds of girls got five A* to C-grade GCSEs, compared with 57.1% of boys.

Conservative spokesman Nick Gibb said: "After this week's Ofsted report showing that half of our secondary schools are not good enough, this is yet more evidence that the government is failing to deliver the quality of education that parents demand and children need."

Liberal Democrat schools spokesman David Laws said: "This government has managed to undermine the credibility of the exam system while failing to deliver for the majority of students."

He called for a new educational standards authority, and devolution of power to schools.